Maybe, the bottom wheel does not have much room to move, as it would be resting on the motor, where the pully connects if I moved it further.
I have taken off the back housing. I have attached a couple of pictures of what I can see.
It appears there is a bolt through the rod that holds the top wheel, on either side of the rod which appears to be threaded on one side are two cir clips.
Have you seen something similar before, knowing my luck the cir clips will break!